The Dateline episode “Under the Prairie Sky” investigates the disappearance of Nicole Waller, a 31-year-old mother of two in Montana. Her car was found in a remote area on Valentine’s Day, 2013. Her body has never been found — but her on-again, off-again boyfriend Cody Wayne Johnston was arrested and charged with deliberate homicide and tampering with physical evidence in 2015. According to authorities, after Waller’s murder, Johnston had asked three people to log on to Waller’s Facebook account and send fake messages saying she was alright. Johnston reportedly told one of them he wanted it done because police had been “hounding” him about Waller’s disappearance.

After two hours of deliberation, a jury found Johnston guilty. He was sentenced to life in prison. Dateline’s Josh Mankiewicz reports: “Cody’s position is, ‘I’m not a killer. Nicole vanished for some reason only Nicole understands.'” Dateline NBC airs Sundays at 7pm.

The Dateline episode “Under the Prairie Sky” investigates the disappearance of Nicole Waller, a 31-year-old mother of two in Montana. Her car was found in a remote area on Valentine’s Day, 2013. Her body has never been found — but her on-again, off-again boyfriend Cody Wayne Johnston was arrested and charged with deliberate homicide and...